1. Field of the Invention
The present invention is directed to a process for producing tubular film packages having a partition to maintain different materials on either side of the partition. More particularly, the present invention is directed to a method of producing mine roof bolt resin packages in which a polymerizable resin component an a catalyst are temporarily maintained on opposing sides of a partition in a tubular package.
2. Description of Related Art
Mine roof bolts and other structural elements are often anchored into rock, concrete or the like by a combination of adhesives and mechanical structures such as an expansion anchor at the distal end of the bolt. Adhesives are generally formed in place within the borehole by providing a resin cartridge that is a dual compartment package containing a polymerizable resin in one compartment and a hardener or catalyst in another compartment. A borehole is drilled in the rock and the cartridge containing the polymerizable resin and catalyst is inserted into the blind end of the borehole. When a mine roof bolt is inserted into the borehole, the distal end of the bolt ruptures the package so that the resin and catalyst are mixed. Typically, the bolt is rotated to enhance mixing until the resin hardens to a degree that the bolt can no longer be rotated and the resin is allowed to cure.
In these two component packages, it is critical that the polymerizable resin and the catalyst are maintained separate from each other until the package is ruptured during installation of the mine roof bolt. Some resin cartridges include an inner compartment containing catalyst surrounded by an outer compartment containing the polymerizable resin. Other resin cartridges employ a barrier to divide a container into two compartments with the catalyst and resin on opposing sides of the barrier. In an aggressive environment such as an underground mine, resin cartridges are often produced from strong films such as polyethylene terephthalate, such as Mylar®. Polyethylene terephthalate provides the desired structural integrity to the resin cartridge, yet is more costly than other pliable films that may be used in less aggressive environments. Conventional resin cartridges often use polyethylene terephthalate for the outer compartment as well as the inner compartment of the barrier, even though these inner structures are not exposed to the underground mine environment and do not require the structural integrity of the outer compartment.
Resin cartridges are produced via various techniques. For example, a resin cartridge having an interior barrier for separating the reactive components can be produced by forming a web of film into an advancing tube with the edges of the tube overlapping each other to produce a tube with an inner web spanning the diameter of the tube. The web is sealed to the tube thereby creating two adjacent compartments with the web being common to both compartments as a barrier. Resin cartridges with a barrier layer that spans a tube have also been produced by forming an advancing tube using a cylindrical forming member. As the tube advances, a strip of film material is advanced through the tube and heat sealed to opposing sides of the tube. However, the heat seals between the barrier and the tubing present an opportunity for failure of the resin cartridge and premature mixing of the polymerizable resin and catalyst.
Alternatively, two compartment packages can be formed by drawing a web of film into a cylindrical forming member to bring the web's edges together in an overlapping relationship and advancing the resulting first tube past the forming member. A second web of pliable film is fed through another forming member to produce a second tube that advances within the advancing first tube at a rate substantially equal to the rate of advancing of the first tube. The first tube is advanced by pinching the edges of the first tube between two pairs of opposing rollers, and the second tube is advanced by similarly pinching the edges of the second tube between two pairs of opposing rollers. This process requires that the advancing rollers for the first tube and the advancing rollers for the second tube are properly matched so both tubes advance at the same rate.